“The biochemistry of Silicon in plants is a riddle, wrapped in a mystery inside an enigma.” — (Epstein, 2001)
Here’s the science…
Plant roots take up Silicon, chemical symbol ‘Si’, in the form of silicic acid (Si(OH)4), it is then transported from the roots to the shoots via the xylem and distributed around the plant organs depending on transpiration rates of each plant organ. The epidermal cell walls are impregnated with a layer of Si, and become effective barriers against water loss by cuticle transpiration and fungal infections.
There are two hypotheses for how Silicon protects a plant. The first one says that the Si acts as a physical barrier, the Si is deposited beneath the cuticle to form a Cuticle-Si double layer and protects the plant mechanically by withstanding pest and disease penetration into the leaf. The other method says that plants supplied with Si produce phenolics, lignin, H2O2, and phytoalexins in response to fungal infection.
Silicon alleviates various abiotic stresses, including physical stress (drought, radiation, high and low temperatures, and freezing), and chemical stress (salt, metal toxicity, and nutrient imbalance). Si relieves water stress by decreasing transpiration, as this mainly occurs through the stomata, and partly through the cuticle, Si deposited below the cuticle may decrease any losses.
Lastly, Silicon is not a mobile element, so any deficiencies will show up on younger leaves. It is not classed as an essential nutrient as a plant can grow and reproduce without it, but for many gardeners, including myself, it is a crucial part of my feeding regime.
Silicon in the grow room…
I know some of you reading this may think, “I’ve never used Silicon before and I’m doing great”, but that’s just like saying “I built a house from just bricks and mud and it looks good to me”. Well, if you added cement to those bricks, you could have a bigger house, and one that’s going to stay up a lot longer. Silicon is the cement in that metaphor and including it will give your plant extra support, improved growth, and bigger yields.
There are a lot of silicon products on the market, and some companies say that their Silicon product does not affect pH as dramatically as others, this is a marketing trick and although it’s true what they say, it’s because they have likely watered down the silica so its effect on pH is not as drastic. Don’t be fooled by creative marketing.
Lastly, the method of adding the silica to the nutrient tank is very important. Here’s what you should be doing to prevent the solution from becoming cloudy, which means the silica has precipitated out of the solution, and become less available to the plant. Firstly, add the silica to your water tank and measure pH, next step is to reduce the pH to 7 and add the rest of your nutrients, lastly adjust pH to desired range depending on the type of plant being grown, this is typically between 5.8 and 6.3. This method, although time consuming is best practice for getting the most out of your plants whilst using silica.
I hope this first article in the ‘What is…’ series has been beneficial to you, and that you feel that Silica is an additive worthy of your feeding regime. I can tell you, with good authority, that it definitely isn’t a Silly-Con…
Myself in a nutshell - Science fanatic, hydroponics obsessed and book worm! Bachelor of Science in Outdoor Education and Geography, MSc in nutrition and scientific investigation, commence Ph.D. in October 2017, researching the effect of different ratios of cannabinoids in the human body.
Motto: The more you learn, the less you know!